Constant velocity joints connecting shafts to drive units are common components in automotive vehicles. The drive unit typically has an output shaft or an input shaft for receiving the joint. Typically, the drive unit is an axle, transfer case, transmission, power take-off unit or other torque device, all of which are common components in automotive vehicles. Typically, one or more joints are assembled to the shaft to form a propeller or drive shaft assembly. It is the propeller shaft assembly, which is connected, for instance, at one end to an output shaft of a transmission and, at the other end, to an input shaft of a differential. The shaft is solid or tubular with ends adapted to attach the shaft to an inner race of the joint thereby allowing an outer race connection to a drive unit. The inner race of the joint is typically press-fit, splined, or pinned to the shaft making the outer race of the joint available to be bolted or press-fit to a hub connector, flange or stubshaft of the particular drive unit. At the other end of the propeller shaft, the same typical or traditional connection is made to a second drive unit when connecting the shaft between the two drive units. Connecting the shaft to a drive unit via the constant velocity joint in this manner is considered a traditional connection. Direct torque flow (DTF) connection is a newer connection style that has advantages and improvements over the traditional connection.
A DTF connection differs from a traditional connection in that an outer race is connected to the shaft that extends between different joints, and an inner race is connectable to a drive unit. One example of a DTF connection provides that the outer race of a constant velocity joint (CVJ) is friction welded to a propeller shaft and the inner race of the CVJ includes a female spline that is connectable to a journal shaft of a transmission. The inner race of the CVJ is rotationally secured by a splined connection directly to the journal shaft, thereby providing an indirect connection to the transmission. In order to retain the CVJ on the shaft, axial retention is required between the inner race and the shaft. For example, a circlip engaging a groove in the inner race and on the shaft may be utilized to retain the two parts. In order to retain lubricant within the joint and thereby sealing out debris, a roll or convoluted boot is connected between the inner race and the outer race. The boot may or may not include a boot shroud. However, axial and radial clearances of the joint at the connection interface for accommodating the boot or shroud may require a decrease in torque transfer capability or may require an increase in the joint design envelope. A decrease in torque transfer capability reduces the overall joint performance and an increase in the design envelope may extenuate unwanted noise and vibration excitations. Moreover, a boot connected between the inner race and the outer race makes inspection of the races more difficult.
It would be advantageous to have a DTF constant velocity joint that overcomes the limitations indicated above. Moreover, it would be advantageous to have a DTF constant velocity joint that provides for a connection to a drive unit while reducing radial and axial clearances, including a reduction in overall design envelope. Furthermore, it would be advantageous to provide a DTF CVJ that improves inspection capability of the connection interface.